I know where a couple are, but I don't think either one is currently for sale.
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| 4340 Billet Crank https://slantsix.org/forum/viewtopic.php?t=57536 |
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| Author: | Landons65Dart [ Sat Apr 18, 2015 8:46 am ] |
| Post subject: | 4340 Billet Crank |
Hello fellow Sixer fanatics! I'm building a 30+ psi 225 with a compound turbo setup. Should I look into a billet crank? I know there's some in existence.. But where? Anyone know who would get rid of such an anomaly? Should I look into getting one made? |
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| Author: | slantzilla [ Sat Apr 18, 2015 2:00 pm ] |
| Post subject: | |
I know where a couple are, but I don't think either one is currently for sale.
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| Author: | CNC-Dude [ Sat Apr 18, 2015 4:06 pm ] |
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I know a Slant racer that got a Crower billet one recently. They're about $4K. You have to think you'd break about 40 stock cranks to justify it though unless you just have money burning a hole in your pocket. |
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| Author: | NEVjr [ Sat Apr 18, 2015 4:35 pm ] |
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Quote: I know a Slant racer that got a Crower billet one recently. They're about $4K. You have to think you'd break about 40 stock cranks to justify it though unless you just have money burning a hole in your pocket.
probably worth blowing up a couple to see how much they would handle
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| Author: | Landons65Dart [ Sat Apr 18, 2015 4:56 pm ] |
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Okay cool all I needed to hear |
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| Author: | Landons65Dart [ Sun Apr 19, 2015 2:32 am ] |
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You guys think a '70 forged crank would handle 35 pounds of boost? |
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| Author: | Charrlie_S [ Sun Apr 19, 2015 3:33 am ] |
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It's not only about the crank. You need to worry about the main bearing caps, and webs. I think you will need to do some upgrading in that area. |
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| Author: | Dart270 [ Sun Apr 19, 2015 5:13 am ] |
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I would say it's more about RPMs than boost. I don't see why not. Keep it under 6000 and it'll live. Charlie is right that the block/main caps should be treated well. Lou |
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| Author: | Landons65Dart [ Sun Apr 19, 2015 8:02 am ] |
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Well I was looking into the mains first which is what brought me to the crank. I asked my machinist if I should run some 4130 mains since there's only 4, and he said the 1045 would be strong enough since the crank would probably go before the mains |
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| Author: | slantzilla [ Sun Apr 19, 2015 11:50 am ] |
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The only guys I have ever seen have any crank issues were grinding them down to Chevy rod journal size. |
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| Author: | Landons65Dart [ Sun Apr 19, 2015 1:07 pm ] |
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Alright. We'll see what happens. Main material..? 1044 isn't strong enough for 35 pounds of boost in my opinion. 4130.. 4340? Let me hear some ideas. |
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| Author: | Will [ Sun Apr 19, 2015 6:47 pm ] |
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Quote: The only guys I have ever seen have any crank issues were grinding them down to Chevy rod journal size.
I have a crank that may resemble that..... As some one that has destroyed a slant in every way possible I think that the crank and mains are not to worry about.Will |
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| Author: | CNC-Dude [ Sun Apr 19, 2015 7:47 pm ] |
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Quote: Alright. We'll see what happens.
You can always do a main girdle to stiffen the block. But you aren't going to break a crank because of the main caps, you will break it because it only has 4 mains and most all other inline 6 cylinder engine blocks have 7. It just doesn't have enough journal support and a lot of journal overlap that makes the design weak. Even with a billet crank with only 4 mains, it will break before the same engine that has 7 mains. Just because its billet doesn't mean it still can't break.
Main material..? 1044 isn't strong enough for 35 pounds of boost in my opinion. 4130.. 4340? Let me hear some ideas. |
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| Author: | Landons65Dart [ Sat May 02, 2015 10:45 am ] |
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That's right and I totally agree. However, since it's such a weak design, I'm trying to build it up as strong as possible to withstand a beating. I know it will still have limits, but I want to overcome as much as I can. I need to make sure the lower end of the rotating assembly will survive. I've already got 2,500 dumped into a block and parts and don't even have my mains ordered. Anyone know of someone that's built a main girdle for a slant? It can't be easy since the mains pertrude below the block's surface. |
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| Author: | Rick Covalt [ Sat May 02, 2015 1:29 pm ] |
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Here is Howard Davis' amazing engine main girdle. After you build that then you need to build a custom pan ....etc to go with it. http://slantsix.org/forum/viewtopic.php ... llside+six Quote: since it's such a weak design,
I am not at all sure I agree that it is a inherently weak design. Maybe in the extreme applications like you are talking about it needs some consideration. But there are a lot of people that have gone pretty fast with a plain Jane forged (or cast) crank. If it was a really weak design the cast cranks would be laying in great heaps outside of garages all over America. Keep the RPM's reasonable and the crank should be fine. Rick |
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